90 Degree Stub-Up Calculator
By Andrew ·
Quick answer
To find the mark for a 90° stub-up, subtract the bender's deduct (also called take-up) from the stub length, and mark that far from the end. Mark = stub − deduct. A typical 1/2" EMT hand bender deducts 5", so a 12" stub is marked at 7". Put the mark on the arrow, hook toward the stub end, and bend until plumb.
Calculator
- Results
- Mark the conduit at (from the stub end)
- 7"
Worked out the textbook way, from the bend angle alone. BendMate also uses your bender’s radius, deduct and shoe.
What the deduct is
A bend uses up conduit. The deduct is the distance from the arrow on the bender to the back of the finished 90, which is the outside of the bend, where you measure the stub. Mark the conduit that far short of the stub length and the stub comes out right.
mark = stub − deductThe deduct is set by the shoe: its radius, half the conduit diameter, and the short straight between the arrow and the start of the bend. Every size has its own, and different makes of the same size can differ.
Typical hand-bender deducts for EMT
| EMT size | Deduct | Mark for stub |
|---|---|---|
| 1/2" | 5" | 13" |
| 3/4" | 6" | 12" |
| 1" | 8" | 10" |
| 1-1/4" | 11" | 7" |
Worked example: a 12" stub in 1/2" EMT
- Stub length
- 12"
- Bender deduct
- 5"
- Mark
- 12" − 5" = 7" from the end
- Mark the conduit at that distance from the stub end.
- Put the mark on the arrow with the hook toward the stub end.
- Pull until the stub is plumb and check it with a level.
- Measure from the end to the back of the bend to confirm the stub length.
Where stub-ups go wrong
- Measuring the stub to the center of the conduit rather than the back of the bend.
- Using the deduct from a different size or make of bender.
- Marking from the wrong end, so the stub comes out as the long leg.
- Stopping the bend short or overbending, which leaves the stub off plumb.
- Asking for a stub shorter than the deduct. The mark would fall off the end of the conduit.
The cut length, too
A 90 saves conduit by going round the corner, so a run with two legs is shorter than the legs added together. In BendMate the same math accounts for your bender’s radius and deduct, and gives the cut length from both legs.
Get the marks for your bender
BendMate works this out from your bender’s radius and deduct, flags a bend that won’t work, and shows you every mark.
Common questions
What is the deduct for a 1/2 inch EMT bender?
Most 1/2" EMT hand benders deduct 5". Benders differ, so use the figure printed on yours.
What is take-up on a conduit bender?
Take-up is another name for the deduct: how much shorter than the stub length you mark the conduit, because the bend uses up that length.
How do you calculate where to bend a 90?
Subtract the deduct from the stub height. With an 18" stub on a 1/2" EMT bender that deducts 5", the mark is at 13".
Which way does the hook face for a stub-up?
Put the mark on the arrow with the hook pointing toward the end that will become the stub. A 90 is always marked for the arrow, because the deduct is measured to it.